Dewatering aids are employed in several solid/liquid separation applications including pulp & paper industry. In the practice of solid/liquid separation, flocculating auxiliaries are added in order to achieve the best possible result in terms of dry substance of the solid and clarity of the filtrate. In other words, it is the object to bring about the most complete separation possible of the solid phase from the liquid phase.
Flocculating auxiliaries are produced in the form of powdery granules or water-in-water or water-in-oil emulsions, and prior to their use are added in dilute aqueous solutions to the medium to be flocculated. Powdery granules can be advantageous, since they can be transported more inexpensively by virtue of their almost anhydrous condition and, as in the water-in-oil emulsions, do not contain any oil or solvent constituents that are insoluble in water.
The use of dry powder mixtures of different polymers in flocculation processes can lead to faulty proportioning as a result of phase-separation phenomena.
EP 262 945 A2 discloses cationic flocculation auxiliaries composed of two different polymer components and methods for their production. The auxiliaries are formed by polymerization of cationic monomers to a high molecular weight cationic polymer component (flocculent) in the presence of a low molecular weight cationic polymer component (coagulant). During this polymerization reaction, the polymer added first can undergo graft reactions. The ratio of coagulant to the high molecular weight cationic polymer component is specified as preferably 5:1 to 1:1.5. Such high proportions of coagulant, however, cause viscosity problems in the production of polymerization solutions. The properties of these flocculating agents do not satisfy the requirements of speed and effectiveness imposed on technical flocculation processes.
US2007/0032677 and US2007/0173586 disclose cationic polymer compositions showing good flocculation performance but possess high levels of insolubles after being dispersed in water. These insolubles can cause severe issues in the customer processes, like e.g. plugged filters, holes in the paper or breaks in the production.
WO 2013/179139 discloses compositions and methods of making paper products.
There is a demand of polymer compositions that overcome the drawbacks of the prior art.
Additional objects, advantages, and features of what is claimed will be set forth in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by the practice of the technology. The objects and advantages of the presently disclosed and claimed inventive concepts will be realized and attained by means of the compositions and methods particularly pointed out in the appended claims, including the functional equivalents thereof.
Each of the reference cited in the present application, including books, patents, published applications, journal articles and other publications, are incorporated herein by reference in their entirety.